The present invention relates to tamper-indicating devices used in combination with closures, and more particularly, to tamper-indicating devices which respond to stimulation from ambient elements such as light.
The average consumer has an increased awareness of the need for containers for consumables such as food, vitamins, medicines and the like which include devices that would give an indication that, subsequent to factory packaging, the container had been opened and the contents possibly tampered with. There have been many attempts to provide such containers. For example, some manufacturers of over-the-counter drugs have begun packaging their drugs in a container that is sealed within a second container, the latter of which must be destroyed in order to reach the inner container. A disadvantage of this type of packaging is that, while it does afford some measure of protection and reassurance to the ultimate purchaser, the cost of packaging is literally doubled, since two containers are required instead of one.
Another solution to this problem, which is particularly adapted to use with bottled consumables such as vitamins or pain relievers, is to provide a paper or foil sheet which covers the bottle opening beneath the cap and is attached by pressure sensitive adhesives to the top of the bottle neck. To gain access to the interior of such a bottle, it is necessary to puncture or remove the sheet, so that a sheet which is damaged in any way would indicate that it would be unsafe to use the contents of the bottle. While considerably less expensive to implement than the aforementioned device, the use of an adhesive sheet has a disadvantage in that it is relatively easy to defeat. For example, the bottle cap can be unscrewed and the adhesive sheet removed from the bottle neck by a glue solvent, steaming or separation using a razor blade, then reattached. If the removal would be performed successfully, the sheet would give no indication that it had been removed and the contents of the bottle exposed.
A refinement of this type of device is disclosed in the Brochman U.S. Pat. No. 3,923,198 and Cornell U.S. Pat. Nos. 3,896,965 and 3,935,960. The Brochman and Cornell '965 patents each disclose a tamper indicator, particularly adapted for use with a can-type container for holding liquid consumables, such as fruit juices, and consists of a strip having a pressure sensitive adhesive on its underside for attachment to the top of the can to cover an opening formed in the top, and a stress-opacifiable material on a top layer. Attempts to remove the strip by pulling it from the top of the can causes the stress-opacifiable material to change in appearance and thereby provide a permanent indication that the top had been removed.
In the Cornell '960 patent, a tamper-indicator tape is disclosed which includes an upper layer having encapsulated, color-forming material. An attempt to remove the tape from the can top causes the capsules to rupture and the material to react with a dye precursor to form a colored dye which changes the appearance of the strip and indicates that the closure has been tampered with. A disadvantage with all of these tamper-indicating strips is that they are susceptible to removal from their associated containers by means which would not necessarily activate their appearance-changing mechanisms. For example, it is conceivable that an adhesive solvent could be utilized to dissolve the pressure sensitive adhesive of their lower layers to effect removal from the can, or that a razor blade could be used to separate the adhesive from the can surface.
Another disadvantage with all of the aforementioned tamper-indicating devices is that they are designed specifically and exclusively for use with bottle-type containers. Many types of consumables are packaged in bags formed from low density polyethylene sheets which are heat sealed along peripheral edges to form the container. It is conceivable that such containers could be opened, the contents adulterated or removed, and the opening resealed, without leaving an indication that this activity had occurred. Another disadvantage comes from handling abuses--from the initial packaging stage there can be impact abuse during loading and unloading from trucks, bumping abuse during shipments, and pressures applied during pricing and stocking stages as well as during handling by potential consumers. In such cases, the abuses could cause stress-opacification and/or capsule rupture even though the contents have not been disturbed.
Accordingly, there is a need for a tamper-indicating device which is relatively inexpensive to manufacture and implement, so that the overall cost of packaging is not increased to a prohibitive level. Furthermore, there is a need for a tamper-indicating device which is more difficult to defeat than the aforementioned prior art devices, which can be removed from the container to be protected, then re-attached without activating the indicator elements. It is also desirable that such a tamper-indicating device be capable of use with polyethylene bags having heat sealed borders as well as the commonly used capped bottles.